If your heater is only blowing cold then it could be due to a plugged heater core. Your heater core is inside your dash and the warmed coolant that comes through your engine flows through it providing heat to you. If this element is plugged then it won't allow the warmed coolant to enter causing you to not have heat. Your heater core can become plugged due to contaminated coolant. Your coolant should be serviced every 36 months/3 years. Give us a call to schedule your appointment and let us take care of you.